Related links:

Smog

Smog is a type of air pollution. Smog is a mixture of smoke and fog. Smog usually forms when smoke from pollution mixes with fog. For example, London, England, is often very foggy. Most people in London used to heat their homes by burning coal. The coal made lots of smoke, which mixed with fog to form smog. London used to have a lot of smog.

There is a special kind of smog called photochemical smog. It forms when photons of sunlight hit molecules of different kinds of pollutants in the atmosphere. The photons make chemical reactions happen. The pollution molecules turn into other kinds of nasty chemicals. That mixture of bad chemicals is called photochemical smog.

The chemicals in photochemical smog include nitrogen oxides, Volatile Organic Compounds (VOCs), ozone, and PAN (peroxyacytyl nitrate). Nitrogen oxides mostly come from the engines of cars and trucks. VOCs are given off by paint, gasoline, and pesticides. Ozone is a form of oxygen that is harmful. PAN is a type of pollution that is made by chemical reactions between other kinds of pollution.

Smog smells bad and makes it hard for people to breath. It can also damage materials. Smog is a very harmful kind of air pollution.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

You might also be interested in:

Photons are little bits of light. Photons carry energy. When a photon hits a molecule, it adds energy to the molecule. The molecule has chemical bonds (they work a bit like stretchy rubber bands!) holding...more

Most things around us are made of groups of atoms connected together into packages called molecules. Molecules are made from atoms of one or more elements. Some molecules are made of only one type of...more

PAN (Peroxyacytyl nitrate) is a kind of air pollution. It is part of smog. PAN makes people's eyes hurt and it is bad for your lungs. It also damages plants. PAN forms when some other kinds of chemicals...more

When you think of chemistry, do you think about mixing colored liquids in test tubes and maybe making an explosion... or at least a nice puff of smoke? Did you know that a lot of chemistry happens in Earth's...more

There is more nitrogen gas in the air than any other kind of gas. About four out of five of the molecules in Earth's atmosphere is nitrogen gas! A molecule of nitrogen gas is made up of two nitrogen atoms....more

There is a group of chemicals called hydrocarbons. The molecules of hydrocarbons are made of hydrogen and carbon atoms. Most kinds of fuel have hydrocarbons in them. Hydrocarbons store energy. Coal, oil,...more

Most of the gas in Earth's atmosphere is nitrogen. About 4/5ths of the air is nitrogen. What about the other 1/5th? Almost all of it is oxygen, the stuff in the air we need to breathe. There are also very...more